Controlling Interfacial Flow Instability via Micro Engineered Surfaces Towards Multiscale Channel Fabrication

Hierarchical branched structures exist in nature in diverse forms, functions and scales stretching from micro to very large sizes. Typically effective as heat and mass transfer networks, ordered hierarchal/ multiscale branched/ tree-like networks could be fabricated by controlling a fluid reshaping process in a device called ‘Multiport Hele-Shaw cell’. Control over the instability by employing micro-modified cell plates, containing ‘source-holes’ as ports, rearranges the fluid into ordered tree-like networks. Reshaping is an outcome of ‘Saffman-Taylor interface instability’ induced by the displacement of a high-viscous fluid by a relatively low-viscous one in the cell. A new configuration of ‘source-holes’, is proposed here to control the instability towards shaping of high-viscous fluid into ordered multiscale treelike layouts. The process is lithography-less method of shaping the fluid spontaneously into 3D layouts in a very short interval of time. Fabricated structures are UV-cured and cast into channel-networks in an elastomer PDMS.